This invention relates to a control lever assembly for operating a linear actuator. In particular, the invention relates to a control lever for operating a valve stem requiring linear motion. The position of the valve stem may be laterally displaced from the upstanding end of the control lever provided to the operator.
Control of valving systems for the operation of work implements may be accomplished either manually or through solonoid operated arrangements. Manual operation of such valves may occur through lever and linkage means enabling an operator to position the valve stem from either a position adjacent to or remote from the valve stem. At least two parameters dictate the design of a mechanical valve control system. First, the force requirement to set the valve stem must be within the range of strength of a normal operator. Since some valve stems require an excessive amount of force to set, the means for positioning such a valve stem may be accomplished through a lever pivoted remote of the valve stem. Secondly, the control lever must be positioned so that the operator has ready access to the lever. Ready access may be difficult because of the positioning of the valve itself and its associated valve stem. Accordingly, the lever may take a non-linear configuration or a more complex arrangement must be provided through the use of bellcranks and associated link means. More complex systems such as just described suffer from more frequent failures than simple unitarily formed control levers. However, a unitarily formed control lever which is pivoted at one point along its length does not provide true linear motion at the valve stem end for a linear operated valve stem. Therefore, it is necessary to provide some arrangement to convert the rotative motion of the end of a pivoted control lever to a linear motion. This has been done by a cross head arrangement or a slotted control lever. Although slotted control levers with a fixed pivot point suffice in some cases, such an arrangement may suffer from undue wear of the valve stem acting against the defined slot. Finally, control levers of any design provide a convenient hand-hold for operators in mounting or dismounting a machine. Such use may cause severe sideloading to the associated valve stem causing premature failure. Since use of such a lever as a hand-hold is unavoidable, the lever and supporting structure must prevent unwanted side loads from reaching the valve stem.